A halogen lamp is very approximate in energy distribution to a full radiator and therefore exhibits excellent color rending properties. Furthermore, a color temperature of light emitted from the halogen lamp is able to be changed in accordance with a magnitude of power supplied to the halogen lamp and thus the halogen lamp is used as a visible light source. However, since the halogen lamp emits infrared rays, there are problems, for example, that the halogen lamp becomes extremely high in temperature, needs a reflector to prevent infrared radiation, has a shorter operating time than an LED, and requires large power consumption. Then, a white light-emitting device that uses a light-emitting diode (LED) which generates less heat and has a longer operating time has been developed.
PTL 1 (Japanese Unexamined Patent Application Publication No. 2014-194858) describes an inexpensive and useful LED lighting device that includes a semiconductor light-emitting device having three or more different color temperatures, in which a color temperature is controlled in a relatively wide range and a natural change in the color temperature is achieved along a blackbody radiation, and desired chromaticity adjustment is allowed by a simple method without requiring complicated control.